The invention relates to Doppler radar, and more specifically to an improved radar signal processing system for discriminating between different aircraft types and ground clutter to identify helicopters.
For certain radar applications, it would be advantageous to be able to identify those targets which represent helicopters. U.S. Pat. No. 4,389,647 discloses a radar system directed to provide this capability. As understood, however, the system disclosed in this patent would not operate as well for low Doppler (i.e., low velocity) helicopters, is not readily applicable to scanning radar systems, and requires relatively long acquisition times to identify a helicopter target.
U.S. Pat. Nos. 4,346,382 and 4,275,396 describe radar systems for detecting helicopters. As understood by applicant, in each of these systems the helicopter detection is accomplished by detecting the modulation induced on the radar return signal by the rotor blades, i.e., detecting the rotor blade flashes. This implies that the required time on target is relatively long, which may prevent use in a scanning surveillance system.
It would therefore represent an advance in the art to provide a radar capable of recognizing helicopter targets within a relatively short acquisition time and which is operable for low Doppler helicopters.
It would further be advantageous to provide a scanning surveillance radar capable of recognizing helicopter targets.